I think its popularity was a product of the time. Back then the show was downright groundbreaking, and as you had to watch it week to week, the hype and popularity built up over time, and a lot of that was deflated when the show was hit by a writers strike and then the finale which was kind of a polarising shitshow. I'd bet the people that love it watched it while it was airing, and I'd bet most people that watched it after it aired are generally like "eh, it was okay at points"
I mostly watched it while it aired, and while I like it, I don't go out of my way to recommend it to people very often. I think for the time period it was great, it was a big event at the time, but it's clear RDM had no idea where the story was going and watching it again years after the fact makes that so damn obvious. The show had some great cliffhangers and twists which worked really well when you were watching week to week and could talk to your friends about it, not so much if you're binging it 20 years later.
My headcanon is that after world war 3 we lost track of time (for a while; survival was priority) and a lot of records were destroyed / reconstructed, so the dates become fuzzy after world war 3, and by the time of TNG and DS9 those fuzzy dates had become accepted as fact because they didn't know any better. The eugenics wars haven't happened on the canon dates, but whose to say they don't actually happen 10 or 20 years from now? 😛
Real life example, our date system involves numbering based on the birth of somebody that almost certainly didn't exist. It's just widely accepted that Christ was born 2024 years ago. Or would it be 2025 years ago? I'm too tired to figure that out.